This invention relates to balers for forming round bales from a crop windrow.
A conventional, well-known type of such a baler is tractor drawn and includes generally a crop pick up mechanism for transferring the crop rearwardly into the inlet of an expandable bale forming chamber defined by a plurality of endless belts movable longitudinally and vertically of the baler in paths spaced transversely of the baler. Such a baler is exemplified in U.S. Pat. Nos. 4,182,101; 4,121,513; and 4,150,527.
In the operation of these balers it is necessary that the tractor operator steer the tractor, and in turn pull the baler, for a uniform feeding of material into the transversely extended baler forming chamber to form a bale of substantially uniform cross-sectional diameter. When this type of operation does not take place and the baler is drawn in a straight path over the windrow, the crop material is fed into only a portion of the chamber inlet to form a bale of non-uniform diameter.
To relieve the tractor operator from constantly observing the feeding pattern of the crop material into the baler and changing such pattern by manipulating the tractor back and forth across the windrow, it was proposed in U.S. Pat. No. 4,065,192 to steer the baler relative to the tractor by a hydraulic system controlled from the tractor. However, although the tractor could be steered in a straight line, the observation and steering of the baler relative to the tractor required the constant attention of the operator.
The inconvenience of the tractor operator having to look behind to observe the feeding action of the baler was removed by the placement in the tractor cab of a gauge responsive to the variation in tension of an end pair of the chamber defining belts, which indicated to the operator the steering direction of the tractor to pull the baler in a sinusoidal path over the crop windrow. Substantially the same operation for baler feeding of a crop windrow is disclosed in U.S. Pat. No. 4,224,867.
An automatic steering of a baler relative to the tractor is disclosed in U.S. Pat. No. 4,433,533 wherein the relative diameter of a bale being formed is detected at two axially spaced locations on the periphery of the bale and the baler automatically steered in response to a generated signal representative of the relative diameter.
This steering of the baler relative to the tractor, and in turn to the crop windrow results in the feeding of the crop material into that portion of the bale forming chamber corresponding to the bale periphery location having the smaller diameter responsive to the generated signal. Since the baler is steered by a single double acting hydraulic cylinder and the signal generated in response to the effective resistance of two rheostats at the spaced locations the steering movement for a given signal is greater in one direction than the other, and with such steering movements being of a reduced frequency as the bale diameter increases so that irregularities are created in the diameter of the completed bale. The present invention provides an improved automatic steering means for a round crop baler which enables a consistent forming of round bales of a uniform cylindrical shape and density.